JP4014538B2 - High durability water slidable coating and method for forming the same - Google Patents

Description

【００１６】
ここでＡ¹、Ａ²は、それぞれ、２価の炭化水素基、または、−（ＣＨ₂）_i−ＮＨ−ＣＯ−Ｏ−基（ｉは０〜９の整数）、若しくは、酸素である。また、Ｒ¹、Ｒ²は、それぞれ、１価の炭化水素基であり、ｎは２０００以下、好ましくは５０以上１０００以下の整数で平均重合度を表す。さらに、ｐ及びｑは、それぞれ、０〜３の整数であり、ｐとｑの合計は３以上である。一般式［１］のアルコキシ基末端ジメチルシリコーンは、末端にアルコキシ基を有するので、前記滑水性被膜を形成する際に該アルコキシ基部で加水分解及び重縮合反応が生じ、マトリックスとしてのシリカと化学的に結合する。
【００１７】
【化４】

【００１８】
ここでＢは−ＣＦ₃基、または−ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）_3-tＹ_t基、Ｘ、Ｙはそれぞれ１価の加水分解性基、ｔは１〜３の整数、ｒは０〜１２の整数、ｓは１〜３の整数である。一般式［２］のフルオロアルキルシランは、末端に加水分解性基を有するので、前記滑水性被膜が形成する際に該加水分解性基部で加水分解及び重縮合反応が生じ、マトリックスとしてのシリカと化学的に結合する。
【００１９】
また、本発明の高耐久な滑水性被膜は、（１）アルコキシシランを加水分解及び重縮合させることによって被膜のマトリックスとなるシリカゾルを調製する工程と、（２）前記［１］式で表されるアルコキシ基末端ジメチルシリコーンと前記［２］式で表されるフルオロアルキルシランとの混合物に、前記（１）の工程で調製したシリカゾルを添加、混合して塗布液を調製する工程と、（３）基材に前記（２）の工程で調製した塗布液を塗布した後８０℃〜６００℃の熱処理を行う工程とによって被膜を形成することを特徴とする。
【００２０】
【発明の実施の形態】
本発明の高耐久な滑水性被膜は車両用ウィンドシールドガラスのワイパーの摺動面に形成され、該滑水性被膜はマトリックスとなるシリカゾルに、滑水成分となるアルコキシ基末端ジメチルシリコーンと耐久性を付与する成分となるフルオロアルキルシランとが混合されて得られる塗布液を車両用ウィンドシールドガラスのワイパーの摺動面に塗布して得られるものである。
【００２１】
滑水性被膜の膜構成成分であるマトリックスとしてのシリカは、アルコキシシランの加水分解及び重縮合反応を進めることにより得られるシリカゾルを用いる。該シリカゾルの調製は、例えば、アルコキシシラン（例えば、テトラエトキシシラン〔Ｓｉ(ＯＣ₂Ｈ₅)₄〕）と溶媒を所定量混合、攪拌（例えば、約３０分程度）し溶液Ａを得る。なお、溶媒としては、エチルアルコール、イソプロピルアルコールなどの低級アルコール、または、それらの混合溶媒が望ましいが、アルコール類に限らず、エーテル類やケトン類等も用いることができる。一方、酸性水溶液と前記溶媒を混合、攪拌して溶液Ｂを得る。次いで、溶液Ａと溶液Ｂを混合後、室温で攪拌してアルコキシシランの加水分解及び重縮合反応を進めシリカゾルを得る。攪拌時間は、１０分から数日が好ましく、特に３０分から１日が好ましいが、室温以外で攪拌する場合はこれに限定されるわけではない。以上のようにアルコキシシランの加水分解は、前記アルコキシシランを出発原料として、少量の水と塩酸、硝酸、酢酸などの酸触媒を添加し行うことができ、その加水分解物を室温または加熱しながら攪拌することにより重縮合させ、シリカゾルを得ることができる。なお、シリカゾルの調製方法としては、上記の方法に限定されるものではないが、上記のようなアルコキシシランを溶媒で希釈したものと、溶媒で希釈した酸性水溶液を徐々に混合することは、急激な反応を避けることができ、より均質な反応が得られるので好ましい。
【００２２】
なお、アルコキシシランとしては、例えば、テトラメトキシシラン、テトラエトキシシラン、テトラプロポキシシラン、テトラブトキシシラン等のテトラアルコキシシラン類、メチルトリメトキシシラン、メチルトリエトキシシラン、エチルトリメトキシシラン、エチルトリエトキシシラン、プロピルトリメトキシシラン、プロピルトリエトキシシラン等のトリアルコキシシラン類、またはジアルコキシシラン類等を用いることができる。なお上記アルコキシシランの中でもテトラメトキシシラン、テトラエトキシシラン、メチルトリメトキシシラン、メチルトリエトキシシラン、エチルトリメトキシシラン、エチルトリエトキシシランが好ましい。
【００２３】
前記シリカゾルに混合される一般式［１］で表されるアルコキシ基末端ジメチルシリコーンは、シリカゾルのシリカ換算量に対して０．１重量％〜１００重量％、好ましくは０．１重量％〜１０重量％の割合で存在させる。０．１重量％未満では、被膜は十分な滑水性を示さず、１００重量％を超えると、アルコキシ基末端ジメチルシリコーンとシリカゾルとの相溶性が低下し成膜性が著しく低下する。成膜性を考慮すると、前記アルコキシ基末端ジメチルシリコーンは、１０重量％以下とすることがより好ましい。
【００２４】
【化５】

【００２５】
ここでＡ¹、Ａ²は、それぞれ、２価の炭化水素基、または、−（ＣＨ₂）_i−ＮＨ−ＣＯ−Ｏ−基（ｉは０〜９の整数）、若しくは、酸素である。また、Ｒ¹、Ｒ²は、それぞれ、１価の炭化水素基であり、ｎは２０００以下の整数で平均重合度を表す。さらにｐ及びｑは、それぞれ、０〜３の整数であり、ｐとｑの合計は３以上である。
【００２６】
さらに、前記アルコキシ基末端ジメチルシリコーンの平均重合度ｎは、２０００を超えるとシリカゾルへの溶解度が著しく低下して分離困難な不溶物が残留し、成膜性が低下するので２０００以下、特に５０〜１０００が好ましい。５０未満であるとアルコキシ基末端ジメチルシリコーンの揮発性が高くなり、滑水性被膜中に導入しにくくなる。加えてジメチルシリコーン鎖が短いために十分な滑水性を発現することができない。また１０００を超えるとシリカゾルへの相溶性低下して、滑水性被膜中に導入しにくくなる。成膜性等を考慮すると１００〜３００がより好ましい。
【００２７】
加えて、前記アルコキシ基末端ジメチルシリコーンのアルコキシ基の数（ｐ＋ｑ）は３以上であることが重要である。アルコキシ基の数（ｐ＋ｑ）が３未満であるとアルコキシ基の数が少ないためにシリカゾルへの溶解度が減少し成膜性が悪化する。加えてジメチルシリコーンと被膜のマトリックス成分であるシリカとの結合が不十分になり、十分な耐久性を付与することができない。このことからアルコキシ基の数（ｐ＋ｑ）は３以上であることが重要である。
【００２８】
前記シリカゾルに混合される一般式［２］で表されるフルオロアルキルシランは、アルコキシ基末端ジメチルシリコーン１モルに対して２０〜２００モルの割合で存在させる。２０モル未満ではアルコキシ基末端ジメチルシリコーンに対するフルオロアルキルシランの含有量が少なく耐久性の優れた被膜を得ることができず、ワイパー摺動時のジャダーの発生は防止できるものの、ワイパー払拭による膜剥離が生じる。また２００モルを超えるとアルコキシ基末端ジメチルシリコーンに対するフルオロアルキルシランの含有量が多くなり、水滴滑落性（滑水性）が悪化し、ワイパー摺動時にジャダーが発生するという不具合が生じる。
【００２９】
【化６】

【００３０】
ここでＢは−ＣＦ₃基、または−ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）_3-tＹ_t基、Ｘ、Ｙはそれぞれ１価の加水分解性基、ｔは１〜３の整数、ｒは０〜１２の整数、ｓは１〜３の整数である。
【００３１】
前記フルオロアルキルシランとしては、例えばＣＦ₃（ＣＦ₂）₁₁ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、ＣＦ₃（ＣＦ₂）₁₁ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＦ₃（ＣＦ₂）₁₁ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、ＣＦ₃（ＣＦ₂）₉ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、ＣＦ₃（ＣＦ₂）₉ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＦ₃（ＣＦ₂）₉ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、ＣＦ₃（ＣＦ₂）₇ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、ＣＦ₃（ＣＦ₂）₇ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＦ₃（ＣＦ₂）₇ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、ＣＦ₃（ＣＦ₂）₅ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、ＣＦ₃（ＣＦ₂）₅ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＦ₃（ＣＦ₂）₅ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、ＣＦ₃ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、ＣＦ₃ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＦ₃ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、ＣＦ₃（ＣＦ₂）₁₁ＣＨ₂ＣＨ₂ＳｉＣｌ₃、ＣＦ₃（ＣＦ₂）₁₁ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、ＣＦ₃（ＣＦ₂）₁₁ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ、ＣＦ₃（ＣＦ₂）₉ＣＨ₂ＣＨ₂ＳｉＣｌ₃、ＣＦ₃（ＣＦ₂）₉ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、ＣＦ₃（ＣＦ₂）₉ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ、ＣＦ₃（ＣＦ₂）₇ＣＨ₂ＣＨ₂ＳｉＣｌ₃、ＣＦ₃（ＣＦ₂）₇ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、ＣＦ₃（ＣＦ₂）₇ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ、ＣＦ₃（ＣＦ₂）₅ＣＨ₂ＣＨ₂ＳｉＣｌ₃、ＣＦ₃（ＣＦ₂）₅ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、ＣＦ₃（ＣＦ₂）₅ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ、ＣＦ₃ＣＨ₂ＣＨ₂ＳｉＣｌ₃、ＣＦ₃ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、ＣＦ₃ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ等の片末端に加水分解性基を有するフルオロアルキルシランや、（ＣＨ₃Ｏ）₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₂ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、（ＣＨ₃Ｏ）₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₂ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＨ₃Ｏ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₂ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、（ＣＨ₃Ｏ）₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₀ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、（ＣＨ₃Ｏ）₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₀ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＨ₃Ｏ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₀ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、（ＣＨ₃Ｏ）₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₈ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、（ＣＨ₃Ｏ）₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₈ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＨ₃Ｏ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₈ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、（ＣＨ₃Ｏ）₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₆ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、（ＣＨ₃Ｏ）₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₆ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＨ₃Ｏ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₆ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、（ＣＨ₃Ｏ）₃ＳｉＣＨ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、（ＣＨ₃Ｏ）₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂ＳｉＣＨ₃（ＯＣＨ₃）₂、ＣＨ₃Ｏ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂ＯＣＨ₃、Ｃｌ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₂ＣＨ₂ＣＨ₂ＳｉＣｌ₃、Ｃｌ₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₂ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、Ｃｌ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₂ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ、Ｃｌ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₀ＣＨ₂ＣＨ₂ＳｉＣｌ₃、Ｃｌ₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₀ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、Ｃｌ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₁₀ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ、Ｃｌ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₈ＣＨ₂ＣＨ₂ＳｉＣｌ₃、Ｃｌ₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₈ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、Ｃｌ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₈ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ、Ｃｌ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₆ＣＨ₂ＣＨ₂ＳｉＣｌ₃、Ｃｌ₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₆ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、Ｃｌ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂（ＣＦ₂）₆ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ、Ｃｌ₃ＳｉＣＨ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂ＳｉＣｌ₃、Ｃｌ₂ＣＨ₃ＳｉＣＨ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂ＳｉＣＨ₃Ｃｌ₂、Ｃｌ（ＣＨ₃）₂ＳｉＣＨ₂ＣＨ₂ＣＦ₂ＣＨ₂ＣＨ₂Ｓｉ（ＣＨ₃）₂Ｃｌ等の両末端に加水分解性基を有するフルオロアルキルシランを用いることができる。また、前記一般式［２］のＸ、Ｙで表される加水分解性基としてはこの他に、エトキシ基、プロポキシ基、イソプロポキシ基、ブトキシ基などのアルコキシ基、または、イソシアネート基等のものを用いることができる。
【００３２】
本発明の滑水性被膜は、前記アルコキシ基末端ジメチルシリコーンのアルコキシ基部およびフルオロアルキルシランの加水分解性基部で加水分解及び重縮合反応が生じるので、高滑水性被膜が形成する際に、前記アルコキシ基末端ジメチルシリコーンおよび前記フルオロアルキルシランは、シリカゾルから得られるマトリックスとしてのシリカと化学的に結合するようになり、耐久性の優れる被膜を得られる。このように、高滑水性被膜中では前記アルコキシ基末端ジメチルシリコーンおよび前記フルオロアルキルシランがシリカマトリックスと結合していることが重要である。この際、シリカマトリックスと化学的に結合していないアルコキシ基部および加水分解性基部が他のアルコキシ基末端ジメチルシリコーンやフルオロアルキルシランと結合していても差し支えない。また、前記アルコキシ基末端ジメチルシリコーンおよび前記フルオロアルキルシランが、他のアルコキシ基末端ジメチルシリコーンおよびフルオロアルキルシランを介してシリカマトリックスと結合していても良い。
【００３３】
なお、ジャダーの発生を防止する滑水性被膜とは、水のしずくや雨滴等で被膜上に水が散水された状態でワイパーブレードを摺動させた際に、ワイパーによる払拭時にワイパーブレードのビビリの発生がなく運転には支障がないレベルにあるものをいう。前記ワイパーブレードに取り付けるワイパーラバーとしては、フッ素樹脂、ナイロン樹脂、ポリイソイミド、グラファイト等がコートされている天然ゴム系のものを用いることができる。
【００３４】
次に、本発明の高滑水性被膜の形成方法について説明する。
【００３５】
本発明の高滑水性被膜は、（１）アルコキシシランを加水分解及び重縮合させることによって被膜のマトリックスとなるシリカゾルを調製する工程と、（２）前記［１］式で表されるアルコキシ基末端ジメチルシリコーンと前記［２］式で表されるフルオロアルキルシランとの混合物に、前記（１）の工程で調製したシリカゾルを添加、混合して塗布液を調製する工程と、（３）基材に前記（２）の工程で調製した塗布液を塗布した後８０℃〜６００℃の熱処理を行う工程、とによって被膜が形成される。
【００３６】
ここで、高滑水性被膜用塗布液の調製方法について説明する。高滑水性被膜用塗布液は、前記一般式［１］で表されるアルコキシ基末端ジメチルシリコーンと前記一般式［２］で表されるフルオロアルキルシランを混合して得られた混合物に前記シリカゾルを添加、混合し、前記アルコキシ基末端ジメチルシリコーンと前記フルオロアルキルシランを加水分解させ、さらに重縮合反応によってマトリックス成分である前記シリカゾルと結合させることにより得ることができる。ここで、アルコキシ基末端ジメチルシリコーンとフルオロアルキルシランとを先に混合するのは、両成分を塗布液中に均質に分散させるためである。
【００３７】
上記で用いる溶媒としては、エチルアルコール、イソプロピルアルコール等の低級アルコール、メチルエチルケトン、メチルイソブチルケトン等のケトン類、酢酸エチル、酢酸ブチル等のエステル類、トルエン、ベンゼン、キシレン等の芳香族系炭化水素溶媒類、ジエチルエーテル、ジイソプロピルエーテル等のエーテル類、クロロホルム、四塩化炭素等の塩素系溶媒やそれらの混合物を用いることが好ましい。
【００３８】
次に、上記で得られた塗布液を基材表面に塗布する。
【００３９】
滑水性被膜を形成するための塗布液の塗布方法としては、手塗り、ノズルフローコート法、ディッピング法、スプレー法、ロールコート法、フレキソ法、印刷法、フローコート法、スピンコート法、それらの併用等各種被膜の形成方法が適宜採用し得る。また、簡易なタイプのスプレー式撥水処理剤などとしても使用することができる。
【００４０】
次に、熱処理を行い、シリカゾルと前記アルコキシ基末端ジメチルシリコーンおよび前記フルオロアルキルシランとの重縮合反応を進行させて、アルコキシ基末端ジメチルシリコーンおよびフルオロアルキルシランとシリカマトリックスとの結合をより強固にさせると同時に、基材表面に高滑水性被膜を固着させる。熱処理温度としては、８０℃〜６００℃が好ましい。熱処理温度が８０℃未満では、アルコキシ基末端ジメチルシリコーンおよびフルオロアルキルシランがシリカマトリックスに十分強固に結合しないだけでなく、高滑水性被膜も基材に十分に固着しないので、結果として耐久性が著しく低下し好ましくない。一方、６００℃を超えるとアルコキシ基末端ジメチルシリコーンやフルオロアルキルシランが熱分解して滑水性が著しく低下するので好ましくない。被膜の耐久性及び製造時の経済性を考慮すると前記熱処理温度は２００℃〜４００℃とすることがより好ましい。
【００４１】
基材の材質としては、ガラス、プラスチック等特に限定されるものではないが、ガラス基材の場合には、車両用窓ガラス等に通常使用されているフロ−トガラス、またはロ−ルアウト法で製造されたソーダ石灰ガラス等無機質の透明性があるガラスが好ましく、無色ガラス、または着色ガラス、若しくは、他の機能性膜との組み合わせ、ガラスの形状等に限定されるものではないが、風冷強化や化学強化等の強化処理されたガラス、中間層にポリ塩化ビニリデン（ＰＶＢ）等のプラスチック層を有する合わせガラス等が好ましく、特に、車両用窓ガラスに供せられる強化処理された曲げガラスや合わせ曲げガラスが好ましい。また、被膜の形成は、基材表面の全体であっても、一部分であってもかまわないが、車両用ウィンドシールドガラスのワイパー摺動面側に形成させるものとする。
【００４２】
本発明における滑水性とは、これらの滑水性被膜を車両用ウィンドシールドガラスに実用した際に雨滴飛散性のレベルを表す尺度であり、実施例で述べる方法で評価される転落角で示されるものである。
【００４３】
【実施例】
以下に本発明の実施例について説明する。尚、本発明はこれらの実施例に限定されるものではない。高耐久な滑水性被膜の評価方法を以下に示す。
【００４４】
〔高耐久な滑水性被膜の評価方法〕
（１）接触角
滑水性被膜を有するサンプル表面に、純水約２μｌを置いたときの水滴とサンプル表面とのなす角を接触角計で測定した。なお、接触角計には協和界面科学製ＣＡ−Ｘ型を用い、大気中（約２５℃）で測定した。
（２）転落角
サンプルを水平に保持した状態で、サンプル表面上に５０μｌの純水を滴下した後、サンプルを徐々に傾けていき、水滴が動き始める時点の傾斜角度を転落角（°）とした。なお、転落角は協和界面科学製ＣＡ−Ａ型を用いて大気中（約２５℃）で測定した。
（３）ワイパー摺動試験
高耐久な滑水性被膜を形成した基材に、水道水を被膜面に対して７００ｍｌ／分の散水量で４５秒の散水と１５秒の停止の繰り返し条件で散水しながら、押し圧１６ｇ／ｃｍで接触させた天然ゴム系ラバーを取り付けたワイパーブレードを実車のワイパー駆動システムを用いて作動させた。このとき前記基材の傾斜角度は約３０°であった。ワイパーラバーとしてはマツダ製の撥水用ワイパーラバー（型式、１ＵＴ７−６７−３３Ｈ）を用いた。このときワイパーブレードが１往復したときを払拭回数１回とし、払拭速度４８回／分でワイパーブレードを作動させた。
【００４５】
運転席側の被膜について、摺動前とワイパーを２７万回摺動させた後の接触角及びジャダー評価を行った。ジャダー評価は、ワイパーブレードの下端部やブレード全体の振れ（ビビリ）の発生状態を目視で観察し、ビビリの発生がなく運転に支障がないレベルを「良」、大きなビビリが発生し運転に支障があるレベルを「不良」と判定した。
【００４６】
実施例１
（１）シリカゾルの調製
シリカゾルは、テトラエトキシシラン〔Ｓｉ(ＯＣ₂Ｈ₅)₄：ＴＥＯＳ〕の加水分解及び重縮合反応を進めることにより調製した。図１に、シリカゾルの調製手順と各成分の混合割合（重量比）を示す。
【００４７】
先ず、ＴＥＯＳ；３１２.５ｇとエキネンＦ１（９０重量％のエタノールと１０重量％のイソプロピルアルコールからなる低級アルコールの混合物）；４５０.０ｇを混合し、約３０分間攪拌し溶液Ａを得た。また、６０重量％硝酸水溶液；７.５ｇ、Ｈ₂Ｏ；２１０.０ｇ及びエキネンＦ１；２０.０ｇを混合し、約３０分間攪拌し溶液Ｂを得た。次いで、溶液Ａと溶液Ｂを混合後、約１５時間室温で攪拌することによってシリカゾルを得た。
【００４８】
（２）塗布液の調製
塗布液は、アルコキシ基末端ジメチルシリコーンとフルオロアルキルシランを混合して得られた混合物に上記シリカゾルを添加、混合することによって得た。図２に塗布液の調製手順と各成分の混合割合（重量比）を示す。また、サンプルの作製条件を表１に示す。
【００４９】
【表１】

【００５０】
先ず、酢酸エチルで１重量％に希釈したヘプタデカフルオロデシルトリメトキシシラン〔ＣＦ₃（ＣＦ₂）₇ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃、以降「Ｃ８ＦＡＳ」と省略する〕溶液；０．４３ｇ、酢酸エチルで０．２重量％に希釈した平均重合度が２５０のアルコキシ基末端ジメチルシリコーン〔（ＣＨ₃Ｏ）₃ＳｉＣＨ₂ＣＨ₂｛Ｓｉ（ＣＨ₃）₂Ｏ｝₂₅₀Ｓｉ（ＣＨ₃）₂ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃〕溶液；０．８８ｇ、メチルエチルケトン；７．００ｇとイソプロピルアルコール；７．００ｇを混合し、約５分間攪拌した。次いで、上記シリカゾル；０．７８ｇを添加し、約１５時間室温で攪拌した。次いで、メチルエチルケトン；２７．０６ｇとイソプロピルアルコール；２７．０６ｇを添加し、３０分間攪拌した。以上の方法により、シリカ濃度が０．１重量％、シリカゾルのシリカ換算量に対するアルコキシ基末端ジメチルシリコーンの重量比（以降、「シリコーン濃度」と記載する）が２．５重量％、アルコキシ基末端ジメチルシリコーンに対するＦＡＳのモル比（（フルオロアルキルシランのモル数）／（アルコキシ基末端ジメチルシリコーンのモル数）以降、「ＦＡＳモル比」と記載する）が８１の塗布液を得た。
【００５１】
（３）ガラス基板の洗浄
実車のウィンドシールドサイズ（約１５００ｍｍ×１０００ｍｍ）のフロートガラス表面を研磨液で研磨し、その後水洗及び乾燥を行った。なお、研磨液には、ガラス用研磨剤ミレークＡ（Ｔ）（三井金属鉱業製）を水道水に分散させた懸濁液（１重量％）を用いた。
【００５２】
（４）高耐久な滑水性被膜の形成
上記（２）で調製した塗布液をスピンコート法により上記（３）で準備したガラス基板上に塗布した。先ず、スピンコーター上にガラス基板を設置し、回転速度が８０ｒｐｍの速度で回転させながら約３００ｍｌの塗布液を滴下し、３０秒間回転速度を維持して塗膜の乾燥を行い、良質な透明ゲル膜を得た。次いで、３７０℃で７分間熱処理を行い、室温まで冷却させて無色透明で高耐久な滑水性被膜付きガラスサンプルを得た。
【００５３】
上記［高耐久な滑水性被膜の評価方法］に記載した要領で、得られた高耐久な滑水性被膜付きガラスサンプルの初期性能及び耐久性を評価したところ、表２に示すとおり、転落角は８°と優れた滑水性を示した。また、表３に示すようにワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０８°、８１°と優れた撥水性を示した。またジャダー評価は２７万回摺動後も「良」であり優れたジャダー防止性能を示した。
【００５４】
【表２】

【００５５】
【表３】

【００５６】
実施例２
Ｃ８ＦＡＳ溶液を０．４７ｇ、アルコキシ基末端ジメチルシリコーン溶液を０．７０ｇ用いた以外はすべて実施例１と同じとした。以上の方法によりシリコーン濃度が２．０重量％、ＦＡＳモル比が１１１の塗布液を得た。
【００５７】
結果、無色透明で高耐久な滑水性被膜が得られ、転落角は９°と優れた滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１１０°、８１°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００５８】
実施例３
Ｃ８ＦＡＳ溶液を０．４９ｇ、アルコキシ基末端ジメチルシリコーン溶液を０．６０ｇ用いた以外はすべて実施例１と同じとした。以上の方法によりシリコーン濃度が１．７重量％、ＦＡＳモル比が１３６の塗布液を得た。
【００５９】
結果、無色透明で高耐久な滑水性被膜が得られ、転落角は８°と良好な滑水性を示した。またワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１１１°、８１°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００６０】
実施例４
Ｃ８ＦＡＳ溶液を０．５１ｇ、アルコキシ基末端ジメチルシリコーン溶液を０．４９ｇ用いた以外はすべて実施例１と同じとした。以上の方法によりシリコーン濃度が１．４重量％、ＦＡＳモル比が１７３の塗布液を得た。
【００６１】
結果、無色透明で高耐久な滑水性被膜が得られ、転落角は８°と優れた滑水性を示した。またワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１１０°、９０°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００６２】
実施例５
Ｃ８ＦＡＳ溶液を０．６０ｇ、アルコキシ基末端ジメチルシリコーン溶液を１．２２ｇ用いた以外はすべて実施例１と同じとした。以上の方法によりシリコーン濃度が３．５重量％、ＦＡＳモル比が８１の塗布液を得た。
【００６３】
結果、良質な透明被膜が得られ、転落角は１４°と優れた滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０９°、８７°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００６４】
実施例６
Ｃ８ＦＡＳ溶液を０．５１ｇ用いた以外はすべて実施例１と同じとした。なお希釈溶媒としてさらにｎ−ブタノールを１．４０ｇ加えた。以上の方法によりシリコーン濃度が２．５重量％、ＦＡＳモル比が９７の塗布液を得た。
【００６５】
結果、無色透明で高耐久な滑水性被膜が得られ、転落角は１２°と優れた滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０８°、９０°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００６６】
実施例７
アルコキシ基末端ジメチルシリコーン溶液を１．０５ｇ用いた以外はすべて実施例６と同じとした。以上の方法によりシリコーン濃度が３．０重量％、ＦＡＳモル比が８１の塗布液を得た。
【００６７】
結果、無色透明で高耐久な滑水性被膜が得られ、転落角は１３°と良好な滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０８°、８５°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００６８】
実施例８
アルコキシ基末端ジメチルシリコーン溶液を１．４１ｇ用いた以外はすべて実施例６と同じとした。以上の方法によりシリコーン濃度が４．０重量％、ＦＡＳモル比が６０の塗布液を得た。
【００６９】
結果、無色透明で高耐久な滑水性被膜が得られ、転落角は１４°と良好な滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０８°、８７°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００７０】
実施例９
アルコキシ基末端ジメチルシリコーン溶液を１．７６ｇ用いた以外はすべて実施例６と同じとした。以上の方法によりシリコーン濃度が５．０重量％、ＦＡＳモル比が４８の塗布液を得た。
【００７１】
結果、無色透明で高耐久な滑水性被膜が得られ、転落角は１２°と優れた滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０９°、８８°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００７２】
実施例１０
アルコキシ基末端ジメチルシリコーン溶液を２．１０ｇ用いた以外はすべて実施例６と同じとした。以上の方法によりシリコーン濃度が６．０重量％、ＦＡＳモル比が４０の塗布液を得た。
【００７３】
結果、無色透明で高耐久な滑水性被膜が得られ、転落角は１３°と優れた滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０９°、９２°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００７４】
実施例１１
アルコキシ基末端ジメチルシリコーンの平均重合度を１５０〔（ＣＨ₃Ｏ）₃ＳｉＣＨ₂ＣＨ₂｛Ｓｉ（ＣＨ₃）₂Ｏ｝₁₅₀Ｓｉ（ＣＨ₃）₂ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃〕にした以外は実施例１と同様にした。以上の方法によりシリコーン濃度が２．５重量％、ＦＡＳモル比が４９の塗布液を得た。結果、無色透明で高耐久な滑水性被膜が得られ、転落角は１０°と優れた滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０８°、８７°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００７５】
実施例１２
アルコキシ基末端ジメチルシリコーンの平均重合度を２００〔（ＣＨ₃Ｏ）₃ＳｉＣＨ₂ＣＨ₂｛Ｓｉ（ＣＨ₃）₂Ｏ｝₂₀₀Ｓｉ（ＣＨ₃）₂ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃〕にした以外は全て実施例１と同様にした。以上の方法によりシリコーン濃度が２．５重量％、ＦＡＳモル比が６５の塗布液を得た。結果、無色透明で高耐久な滑水性被膜が得られ、転落角は１０°と優れた滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０９°、８６°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００７６】
実施例１３
アルコキシ基末端ジメチルシリコーンの平均重合度を３００〔（ＣＨ₃Ｏ）₃ＳｉＣＨ₂ＣＨ₂｛Ｓｉ（ＣＨ₃）₂Ｏ｝₃₀₀Ｓｉ（ＣＨ₃）₂ＣＨ₂ＣＨ₂Ｓｉ（ＯＣＨ₃）₃〕にした以外は全て実施例１と同様にした。以上の方法によりシリコーン濃度が２．５重量％、ＦＡＳモル比が９７の塗布液を得た。結果、無色透明で高耐久な滑水性被膜が得られ、転落角は１１°と優れた滑水性を示した。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１０８°、８８°と優れた撥水性を示した。またジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示した。
【００７７】
比較例１
Ｃ８ＦＡＳ溶液を０．２７ｇ、４重量％に希釈したアルコキシ基末端ジメチルシリコーン（平均重合度２５０）溶液を０．８８ｇ添加した以外は全て実施例１と同じとした。以上の方法によりシリコーン濃度が５０重量％、ＦＡＳモル比が２．６の塗布液を得た。
【００７８】
結果、無色透明な被膜が得られ、転落角は８°と滑水性は良好であった。またワイパー摺動試験においてジャダー評価は２７万回摺動後でも「良」であり優れたジャダー防止性能を示したが、２７万回摺動後の接触角は５５°と著しく劣化し、実用に供することのできる被膜を得ることができなかった。
【００７９】
比較例２
アルコキシ基末端ジメチルシリコーンの平均重合度を２００とし、溶液の添加量を０．１８ｇにした以外はすべて実施例１と同じとした。以上の方法によりシリコーン濃度が０．５重量％、ＦＡＳモル比が５５０の塗布液を得た。
【００８０】
結果、良質な透明被膜が得られたが、転落角は２０°と滑水性は悪かった。また、ワイパー摺動試験において初期及び２７万回摺動後の接触角はそれぞれ１１１°、８７°と優れた撥水性を示したが、ジャダー評価は初期、２７万回摺動後ともに「不良」でありジャダー防止性能が十分ではなく実用に供することのできる被膜を得ることができなかった。
【００８１】
比較例３
シリコーン濃度を０重量％とした以外は全て実施例１と同じとした。すなわち、本比較例ではシリカからなるマトリックス中にアルコキシ基末端ジメチルシリコーンを含有せずフルオロアルキルシランのみを含有する被膜を作製した。結果、被膜全面に斑点状跡が発生した。また初期転落角は２７°と滑水性が悪かった。また、ワイパー摺動試験において初期および２７万回摺動後の接触角はそれぞれ１１３°、１００°と優れた撥水性を示したが、ジャダー評価は初期、２７万回摺動後ともに「不良」でありジャダー防止性能が十分ではなく実用に供することのできる被膜を得ることができなかった。
【００８２】
比較例４
シリカ濃度を０重量％とした以外は実施例１と同じとした。すなわち本比較例ではマトリックス成分としてのシリカを含有しない被膜を作製した。結果、無色透明な被膜を得ることはできたが、接触角は７８°、転落角は２０°と撥水性と滑水性ともに悪く、実用に供することのできる被膜を得ることができなかった。
【００８３】
【発明の効果】
本発明の高耐久な滑水性被膜は、高い撥水性と滑水性、およびワイパー等による耐磨耗性に優れており、加えてワイパー摺動時のジャダーの発生を防止するので、車両用のウィンドシールドガラスに用いた場合には、雨天時に前方の視界確保が容易となりさらにワイパーのジャダーも気にならず運転の安全性が向上する。さらには、この効果が長期間にわたり維持できる等の著効を奏する。
【図面の簡単な説明】
【図１】実施例１におけるシリカゾルの調製手順を示す図である。
【図２】実施例１における塗布液の調製手順を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water slidable coating that is excellent in water droplet sliding property and durability suitable for use in a windshield glass for vehicles, and that prevents the occurrence of judder when a wiper slides.
[0002]
[Prior art]
As an attempt to improve the water slidability of the coating, a silicone-based wax, an organopolysiloxane, a composition containing a surfactant, and the like have been proposed. For example, in Patent Document 1, a composition comprising an alkylpolysiloxane and an acid, Patent Document 2 discloses a composition containing an amino-modified silicone oil and a surfactant, and a composition that slides with a water droplet amount of about 15 μl at a 30 ° inclination is obtained.
[0003]
In Patent Document 3,-(CH ₂ ) _Three (CF ₂ ) ₇ CH _Three A group in which a group such as is directly bonded to a silicon atom forming an organosiloxane unit, and-(CH ₂ ) _Three SiCl _Three And a surface treatment agent comprising a fluorine-containing silicone compound and / or a partial hydrolyzate product of the compound in which a unit directly bonded to a silicon atom forming an organosiloxane unit is essential. As a result, 50 μl of water droplets slide down with an inclination of about 10 °.
[0004]
Furthermore, in Patent Document 4, a silicone compound having a hydrolyzable functional group at the terminal, or a silicone compound having a hydrolyzable functional group at the terminal and a fluoroalkyl group at the other end, and acid and water as a solvent A film obtained by applying a mixed solution obtained by mixing and stirring to a substrate surface after being dissolved in the substrate, followed by drying, is chemically bonded to the substrate surface by a siloxane bond. A surface-treated substrate excellent in water drop slidability has been disclosed, and 50 μl of water drop slid at an inclination of about 1 ° has been obtained.
[0005]
However, the surface treatment agents of Patent Document 1 to Patent Document 4 directly form the water-sliding layer by treating the water-sliding component on the base material. It is not sufficient, and further, there is a problem that the durability is poor because the amount of the water-sliding component fixed to the base material is small.
[0006]
For this reason, as a method for strengthening the bond between the base material and the water-sliding component and increasing the amount of the water-sliding component fixed to the base material, a study is also conducted to form a transparent film comprising the water-sliding component and the matrix component on the base material. In Patent Document 5, a solution obtained by hydrolyzing a mixture of a fluoroalkyl group-containing silane compound, dimethyl silicone and / or a derivative thereof in a solvent, and an alkoxysilane compound in a solvent are hydrolyzed. The solution thus obtained is mixed, and this mixed solution is applied to the surface of the substrate, and the fluoroalkyl group and the methyl group are present in a higher concentration in the outer surface layer than in the inner layer of the coating film. An aqueous coating is disclosed.
[0007]
In Patent Document 6, as a film-forming composition that can be formed, at least one kind of crosslinking selected from a hydroxyl group-containing vinyl polymer, an epoxy-terminated siloxane polymer, a sulfonic acid compound, an optionally blocked polyisocyanate compound, and a melamine resin is used. The water-repellent film obtained by the film-forming composition capable of forming a film containing a surfactant selected from the agent component and a specific dialkylsulfosuccinate and alkylene oxide silane has a tumbling angle of 5 ° or less when the water droplet amount is 10 μl And exhibiting excellent performance.
[0008]
However, the above-mentioned Patent Document 5 is a level in which a water droplet having a water drop sliding property of 50 μl slides at an inclination of about 16 °, and is not sufficient for the purpose of good raindrop removal as a vehicle window glass. No technical considerations such as judder evaluation at the time of wiper sliding assuming a level and application to a windshield for a vehicle have been made. Further, Patent Document 6 has low transparency and is limited to use as a paint.
[0009]
In addition, when a film having water slidability and water repellency as described above is used for a windshield glass for a vehicle, when the windshield wiper is operated in the rain, a water film cannot be uniformly formed on the surface of the windshield glass. Since the coating surface is not uniformly contacted, the frictional force between the wiper and the coating becomes non-uniform, and there is a problem that large pulsation (judder) occurs when the wiper slides.
[0010]
For the purpose of reducing the judder, Patent Documents 7 and 8 improve the wiper blade. In Patent Documents 7 and 8, claims are made for the water-repellent coating and the wiper blade, but the reduction of judder is mainly due to the wiper blade. Studies to reduce judder have so far been limited to improvement of wiper blades, and there has never been any attempt to prevent judder by actively improving the coating material.
[0011]
[Patent Document 1]
Japanese Patent Publication No. 50-15473
[Patent Document 2]
JP-A-5-301742
[Patent Document 3]
Japanese Patent Laid-Open No. 11-181212
[Patent Document 4]
JP 2000-144056 A
[Patent Document 5]
JP-A-8-12375
[Patent Document 6]
JP 2000-26758 A
[Patent Document 7]
Japanese Patent Laid-Open No. 6-262934
[Patent Document 8]
JP-A-8-268234
[0012]
[Problems to be solved by the invention]
Water-repellent coating improves water-drop sliding performance and further improves rain-drop scattering performance. In particular, it is an object of the present invention to obtain a highly durable slidable coating that prevents wear caused by a wiper or the like and prevents the generation of judder when the wiper slides.
[0013]
[Means for Solving the Problems]
The present invention has been made in view of the above-mentioned problems, and has been intensively studied on a water-slidable coating film containing a dimethyl silicone as a water-sliding component and a fluoroalkylsilane imparting durability in a matrix made of silica. In addition, it has developed a highly transparent water-resistant coating that is colorless and transparent, and has water slidability and durability, especially wear resistance due to wipers, and prevents the occurrence of judder when the wiper slides.
[0014]
That is, the highly durable water slidable coating of the present invention is a water slidable coating used for windshield glass for vehicles, and an alkoxy-terminated dimethyl silicone represented by the general formula [1] , A coating solution obtained by mixing with a fluoroalkylsilane represented by the general formula [2], wherein the alkoxy group-terminated dimethylsilicone is 0.1% by weight to 100% by weight with respect to the silica equivalent of the silica sol. %, Preferably 0.1% by weight to 10% by weight, and the coating liquid in which the fluoroalkylsilane is mixed so as to be 20 to 200 mol with respect to 1 mol of alkoxy-terminated dimethylsilicone is a vehicle. This coating is applied to the sliding surface of the windshield glass wiper to prevent judder generation when the wiper slides. It is characterized in. The silica-converted amount of the silica sol indicates the amount of silica obtained from the silica sol, and is uniquely derived from the amount of alkoxysilane that is the starting material of the silica sol.
[0015]
[Chemical 3]

[0016]
Where A ¹ , A ² Are each a divalent hydrocarbon group or — (CH ₂ ) _i —NH—CO—O— group (i is an integer of 0 to 9) or oxygen. R ¹ , R ² Are monovalent hydrocarbon groups, and n is an integer of 2000 or less, preferably 50 or more and 1000 or less, and represents the average degree of polymerization. Further, p and q are each an integer of 0 to 3, and the sum of p and q is 3 or more. Since the alkoxy group-terminated dimethyl silicone of the general formula [1] has an alkoxy group at the terminal, hydrolysis and polycondensation reactions occur in the alkoxy group part when forming the water-slidable coating, and the silica and the chemical as a matrix are chemically generated. To join.
[0017]
[Formula 4]

[0018]
Where B is -CF _Three Group, or -CH ₂ CH ₂ Si (CH _Three ) _3-t Y _t Groups, X and Y are each a monovalent hydrolyzable group, t is an integer of 1 to 3, r is an integer of 0 to 12, and s is an integer of 1 to 3. Since the fluoroalkylsilane of the general formula [2] has a hydrolyzable group at the terminal, hydrolysis and polycondensation reactions occur in the hydrolyzable group when the water-slidable coating is formed, and silica as a matrix Bond chemically.
[0019]
The highly durable water-slidable coating of the present invention is represented by (1) a step of preparing a silica sol that becomes a matrix of the coating by hydrolysis and polycondensation of alkoxysilane, and (2) the formula [1]. Adding a silica sol prepared in the step (1) to a mixture of the alkoxy group-terminated dimethylsilicone and the fluoroalkylsilane represented by the formula [2], and mixing them to prepare a coating solution; ) A coating film is formed by applying a coating solution prepared in the step (2) to a substrate and then performing a heat treatment at 80 ° C. to 600 ° C.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The highly durable water slidable coating of the present invention is formed on the sliding surface of a windshield glass wiper for a vehicle. It is obtained by applying a coating solution obtained by mixing with a fluoroalkylsilane serving as a component to be applied to the sliding surface of a windshield glass wiper for vehicles.
[0021]
Silica sol obtained by advancing hydrolysis and polycondensation reaction of alkoxysilane is used for silica as a matrix which is a film constituent of the water slidable coating. The silica sol can be prepared by, for example, alkoxysilane (for example, tetraethoxysilane [Si (OC ₂ H _Five ) _Four ] And a predetermined amount of the solvent are mixed and stirred (for example, about 30 minutes) to obtain a solution A. The solvent is preferably a lower alcohol such as ethyl alcohol or isopropyl alcohol, or a mixed solvent thereof, but is not limited to alcohols, and ethers and ketones can also be used. On the other hand, an acidic aqueous solution and the solvent are mixed and stirred to obtain a solution B. Next, after mixing the solution A and the solution B, the mixture is stirred at room temperature to proceed hydrolysis and polycondensation reaction of alkoxysilane to obtain a silica sol. The stirring time is preferably 10 minutes to several days, and particularly preferably 30 minutes to 1 day, but is not limited to this when stirring is performed at a temperature other than room temperature. As described above, hydrolysis of alkoxysilane can be carried out by adding a small amount of water and an acid catalyst such as hydrochloric acid, nitric acid, acetic acid, etc., using alkoxysilane as a starting material, and heating the hydrolyzate at room temperature or while heating. A silica sol can be obtained by polycondensation by stirring. The method for preparing the silica sol is not limited to the above method. However, gradually mixing the alkoxysilane diluted with the solvent and the acidic aqueous solution diluted with the solvent is abrupt. This is preferable because a more uniform reaction can be obtained.
[0022]
Examples of the alkoxysilane include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane. , Trialkoxysilanes such as propyltrimethoxysilane and propyltriethoxysilane, or dialkoxysilanes can be used. Among the above alkoxysilanes, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane are preferable.
[0023]
The alkoxy group-terminated dimethyl silicone represented by the general formula [1] mixed with the silica sol is 0.1% by weight to 100% by weight, preferably 0.1% by weight to 10% by weight with respect to the silica equivalent of the silica sol. % Present. If the amount is less than 0.1% by weight, the coating film does not exhibit sufficient water slidability. If the amount exceeds 100% by weight, the compatibility between the alkoxy group-terminated dimethylsilicone and the silica sol is lowered, and the film formability is significantly lowered. In consideration of film formability, the alkoxy group-terminated dimethyl silicone is more preferably 10% by weight or less.
[0024]
[Chemical formula 5]

[0025]
Where A ¹ , A ² Are each a divalent hydrocarbon group or — (CH ₂ ) _i —NH—CO—O— group (i is an integer of 0 to 9) or oxygen. R ¹ , R ² Are monovalent hydrocarbon groups, and n is an integer of 2000 or less and represents the average degree of polymerization. Further, p and q are each an integer of 0 to 3, and the sum of p and q is 3 or more.
[0026]
Further, when the average polymerization degree n of the alkoxy group-terminated dimethylsilicone exceeds 2000, the solubility in silica sol is remarkably lowered, and insoluble matters that are difficult to separate remain, and the film formability is lowered. 1000 is preferred. When it is less than 50, the volatility of the alkoxy group-terminated dimethylsilicone increases, and it becomes difficult to introduce it into the water-slidable coating. In addition, since the dimethyl silicone chain is short, sufficient lubricity cannot be expressed. On the other hand, if it exceeds 1000, the compatibility with silica sol is lowered and it becomes difficult to introduce it into the water-slidable coating. In consideration of film formability and the like, 100 to 300 is more preferable.
[0027]
In addition, it is important that the number (p + q) of alkoxy groups in the alkoxy group-terminated dimethyl silicone is 3 or more. When the number of alkoxy groups (p + q) is less than 3, the number of alkoxy groups is small, so that the solubility in silica sol is reduced and the film formability is deteriorated. In addition, the bond between dimethyl silicone and silica, which is a matrix component of the coating, is insufficient, and sufficient durability cannot be imparted. From this, it is important that the number of alkoxy groups (p + q) is 3 or more.
[0028]
The fluoroalkylsilane represented by the general formula [2] mixed with the silica sol is present in a proportion of 20 to 200 mol per 1 mol of the alkoxy group-terminated dimethylsilicone. If the amount is less than 20 mol, the content of fluoroalkylsilane with respect to the alkoxy group-terminated dimethylsilicone is small, and it is not possible to obtain a coating having excellent durability. Arise. On the other hand, when the amount exceeds 200 mol, the content of fluoroalkylsilane with respect to the alkoxy-terminated dimethylsilicone increases, the water drop sliding property (sliding property) deteriorates, and a problem occurs that judder is generated when the wiper slides.
[0029]
[Chemical 6]

[0030]
Where B is -CF _Three Group, or -CH ₂ CH ₂ Si (CH _Three ) _3-t Y _t Groups, X and Y are each a monovalent hydrolyzable group, t is an integer of 1 to 3, r is an integer of 0 to 12, and s is an integer of 1 to 3.
[0031]
Examples of the fluoroalkylsilane include CF _Three (CF ₂ ) ₁₁ CH ₂ CH ₂ Si (OCH _Three ) _Three , CF _Three (CF ₂ ) ₁₁ CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CF _Three (CF ₂ ) ₁₁ CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , CF _Three (CF ₂ ) ₉ CH ₂ CH ₂ Si (OCH _Three ) _Three , CF _Three (CF ₂ ) ₉ CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CF _Three (CF ₂ ) ₉ CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , CF _Three (CF ₂ ) ₇ CH ₂ CH ₂ Si (OCH _Three ) _Three , CF _Three (CF ₂ ) ₇ CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CF _Three (CF ₂ ) ₇ CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , CF _Three (CF ₂ ) _Five CH ₂ CH ₂ Si (OCH _Three ) _Three , CF _Three (CF ₂ ) _Five CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CF _Three (CF ₂ ) _Five CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , CF _Three CH ₂ CH ₂ Si (OCH _Three ) _Three , CF _Three CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CF _Three CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , CF _Three (CF ₂ ) ₁₁ CH ₂ CH ₂ SiCl _Three , CF _Three (CF ₂ ) ₁₁ CH ₂ CH ₂ SiCH _Three Cl ₂ , CF _Three (CF ₂ ) ₁₁ CH ₂ CH ₂ Si (CH _Three ) ₂ Cl, CF _Three (CF ₂ ) ₉ CH ₂ CH ₂ SiCl _Three , CF _Three (CF ₂ ) ₉ CH ₂ CH ₂ SiCH _Three Cl ₂ , CF _Three (CF ₂ ) ₉ CH ₂ CH ₂ Si (CH _Three ) ₂ Cl, CF _Three (CF ₂ ) ₇ CH ₂ CH ₂ SiCl _Three , CF _Three (CF ₂ ) ₇ CH ₂ CH ₂ SiCH _Three Cl ₂ , CF _Three (CF ₂ ) ₇ CH ₂ CH ₂ Si (CH _Three ) ₂ Cl, CF _Three (CF ₂ ) _Five CH ₂ CH ₂ SiCl _Three , CF _Three (CF ₂ ) _Five CH ₂ CH ₂ SiCH _Three Cl ₂ , CF _Three (CF ₂ ) _Five CH ₂ CH ₂ Si (CH _Three ) ₂ Cl, CF _Three CH ₂ CH ₂ SiCl _Three , CF _Three CH ₂ CH ₂ SiCH _Three Cl ₂ , CF _Three CH ₂ CH ₂ Si (CH _Three ) ₂ Fluoroalkylsilanes having a hydrolyzable group at one end, such as Cl, and (CH _Three O) _Three SiCH ₂ CH ₂ (CF ₂ ) ₁₂ CH ₂ CH ₂ Si (OCH _Three ) _Three , (CH _Three O) ₂ CH _Three SiCH ₂ CH ₂ (CF ₂ ) ₁₂ CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CH _Three O (CH _Three ) ₂ SiCH ₂ CH ₂ (CF ₂ ) ₁₂ CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , (CH _Three O) _Three SiCH ₂ CH ₂ (CF ₂ ) _Ten CH ₂ CH ₂ Si (OCH _Three ) _Three , (CH _Three O) ₂ CH _Three SiCH ₂ CH ₂ (CF ₂ ) _Ten CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CH _Three O (CH _Three ) ₂ SiCH ₂ CH ₂ (CF ₂ ) _Ten CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , (CH _Three O) _Three SiCH ₂ CH ₂ (CF ₂ ) ₈ CH ₂ CH ₂ Si (OCH _Three ) _Three , (CH _Three O) ₂ CH _Three SiCH ₂ CH ₂ (CF ₂ ) ₈ CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CH _Three O (CH _Three ) ₂ SiCH ₂ CH ₂ (CF ₂ ) ₈ CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , (CH _Three O) _Three SiCH ₂ CH ₂ (CF ₂ ) ₆ CH ₂ CH ₂ Si (OCH _Three ) _Three , (CH _Three O) ₂ CH _Three SiCH ₂ CH ₂ (CF ₂ ) ₆ CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CH _Three O (CH _Three ) ₂ SiCH ₂ CH ₂ (CF ₂ ) ₆ CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , (CH _Three O) _Three SiCH ₂ CH ₂ CF ₂ CH ₂ CH ₂ Si (OCH _Three ) _Three , (CH _Three O) ₂ CH _Three SiCH ₂ CH ₂ CF ₂ CH ₂ CH ₂ SiCH _Three (OCH _Three ) ₂ , CH _Three O (CH _Three ) ₂ SiCH ₂ CH ₂ CF ₂ CH ₂ CH ₂ Si (CH _Three ) ₂ OCH _Three , Cl _Three SiCH ₂ CH ₂ (CF ₂ ) ₁₂ CH ₂ CH ₂ SiCl _Three , Cl ₂ CH _Three SiCH ₂ CH ₂ (CF ₂ ) ₁₂ CH ₂ CH ₂ SiCH _Three Cl ₂ , Cl (CH _Three ) ₂ SiCH ₂ CH ₂ (CF ₂ ) ₁₂ CH ₂ CH ₂ Si (CH _Three ) ₂ Cl, Cl _Three SiCH ₂ CH ₂ (CF ₂ ) _Ten CH ₂ CH ₂ SiCl _Three , Cl ₂ CH _Three SiCH ₂ CH ₂ (CF ₂ ) _Ten CH ₂ CH ₂ SiCH _Three Cl ₂ , Cl (CH _Three ) ₂ SiCH ₂ CH ₂ (CF ₂ ) _Ten CH ₂ CH ₂ Si (CH _Three ) ₂ Cl, Cl _Three SiCH ₂ CH ₂ (CF ₂ ) ₈ CH ₂ CH ₂ SiCl _Three , Cl ₂ CH _Three SiCH ₂ CH ₂ (CF ₂ ) ₈ CH ₂ CH ₂ SiCH _Three Cl ₂ , Cl (CH _Three ) ₂ SiCH ₂ CH ₂ (CF ₂ ) ₈ CH ₂ CH ₂ Si (CH _Three ) ₂ Cl, Cl _Three SiCH ₂ CH ₂ (CF ₂ ) ₆ CH ₂ CH ₂ SiCl _Three , Cl ₂ CH _Three SiCH ₂ CH ₂ (CF ₂ ) ₆ CH ₂ CH ₂ SiCH _Three Cl ₂ , Cl (CH _Three ) ₂ SiCH ₂ CH ₂ (CF ₂ ) ₆ CH ₂ CH ₂ Si (CH _Three ) ₂ Cl, Cl _Three SiCH ₂ CH ₂ CF ₂ CH ₂ CH ₂ SiCl _Three , Cl ₂ CH _Three SiCH ₂ CH ₂ CF ₂ CH ₂ CH ₂ SiCH _Three Cl ₂ , Cl (CH _Three ) ₂ SiCH ₂ CH ₂ CF ₂ CH ₂ CH ₂ Si (CH _Three ) ₂ Fluoroalkylsilanes having hydrolyzable groups at both ends, such as Cl, can be used. In addition to the hydrolyzable groups represented by X and Y in the general formula [2], those having an alkoxy group such as an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group, or an isocyanate group Can be used.
[0032]
The water-slidable film of the present invention undergoes hydrolysis and polycondensation reaction at the alkoxy group part of the alkoxy group-terminated dimethyl silicone and the hydrolyzable group part of the fluoroalkylsilane, so that when the highly water-slidable film is formed, the alkoxy group The terminal dimethyl silicone and the fluoroalkylsilane are chemically bonded to silica as a matrix obtained from silica sol, and a coating having excellent durability can be obtained. Thus, it is important that the alkoxy-terminated dimethyl silicone and the fluoroalkylsilane are bonded to the silica matrix in the highly water-slidable coating. At this time, the alkoxy group portion and the hydrolyzable group portion that are not chemically bonded to the silica matrix may be bonded to other alkoxy group-terminated dimethyl silicone or fluoroalkylsilane. Further, the alkoxy group-terminated dimethyl silicone and the fluoroalkylsilane may be bonded to the silica matrix via other alkoxy group-terminated dimethylsilicone and fluoroalkylsilane.
[0033]
Note that the water-slidable coating that prevents judder generation refers to the vibration of the wiper blade when the wiper blade is wiped with the wiper when the wiper blade is slid while water is sprayed on the coating with water drops or raindrops. It means that there is no occurrence and there is no trouble in driving. As the wiper rubber to be attached to the wiper blade, a natural rubber type coated with fluororesin, nylon resin, polyisoimide, graphite or the like can be used.
[0034]
Next, the method for forming the highly water-slidable coating film of the present invention will be described.
[0035]
The highly water-slidable coating of the present invention comprises (1) a step of preparing a silica sol that is a matrix of a coating by hydrolysis and polycondensation of alkoxysilane, and (2) an alkoxy group terminal represented by the formula [1] A step of adding a silica sol prepared in the step (1) to a mixture of dimethylsilicone and the fluoroalkylsilane represented by the formula [2] and mixing them to prepare a coating solution; and (3) a base material. A film is formed by applying the coating solution prepared in the step (2) and performing a heat treatment at 80 ° C. to 600 ° C.
[0036]
Here, a method for preparing a coating solution for a highly water-slidable coating will be described. The coating solution for a highly water-slidable coating is obtained by mixing the silica sol with a mixture obtained by mixing the alkoxy group-terminated dimethyl silicone represented by the general formula [1] and the fluoroalkylsilane represented by the general formula [2]. It can be obtained by adding, mixing, hydrolyzing the alkoxy-terminated dimethylsilicone and the fluoroalkylsilane, and further combining with the silica sol as a matrix component by a polycondensation reaction. Here, the reason why the alkoxy-terminated dimethylsilicone and the fluoroalkylsilane are mixed first is to disperse both components uniformly in the coating solution.
[0037]
Solvents used above include lower alcohols such as ethyl alcohol and isopropyl alcohol, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate, and aromatic hydrocarbon solvents such as toluene, benzene and xylene. It is preferable to use ethers such as diethyl ether and diisopropyl ether, chlorinated solvents such as chloroform and carbon tetrachloride, and mixtures thereof.
[0038]
Next, the coating solution obtained above is applied to the surface of the substrate.
[0039]
Examples of coating methods for forming a water slidable coating include hand coating, nozzle flow coating method, dipping method, spray method, roll coating method, flexo method, printing method, flow coating method, spin coating method, and the like. Various film forming methods such as combined use can be appropriately employed. It can also be used as a simple type spray-type water repellent agent.
[0040]
Next, heat treatment is performed to advance a polycondensation reaction between the silica sol and the alkoxy group-terminated dimethyl silicone and the fluoroalkylsilane, thereby further strengthening the bond between the alkoxy group-terminated dimethylsilicone and fluoroalkylsilane and the silica matrix. At the same time, a highly water-slidable coating is fixed to the substrate surface. As heat processing temperature, 80 to 600 degreeC is preferable. When the heat treatment temperature is less than 80 ° C., not only the alkoxy-terminated dimethyl silicone and fluoroalkylsilane are not sufficiently bonded to the silica matrix, but also the highly lubricious coating is not sufficiently fixed to the substrate, resulting in remarkable durability. Decreasing and not preferable. On the other hand, when the temperature exceeds 600 ° C., the alkoxy-terminated dimethylsilicone or fluoroalkylsilane is thermally decomposed and the sliding property is remarkably lowered. In consideration of the durability of the coating and the economical efficiency during production, the heat treatment temperature is more preferably 200 ° C to 400 ° C.
[0041]
The material of the base material is not particularly limited, such as glass or plastic, but in the case of a glass base material, it is manufactured by a float glass or roll-out method that is usually used for vehicle window glass or the like. Inorganic transparent glass such as soda lime glass is preferable, and it is not limited to colorless glass, colored glass, or a combination with other functional films, glass shape, etc., but air cooling strengthening Glass that has been subjected to tempering treatment such as tempering or chemical strengthening, laminated glass having a plastic layer such as polyvinylidene chloride (PVB) in the intermediate layer is preferred, and in particular, tempered bent glass or laminated material used for vehicle window glass Bent glass is preferred. Further, the coating may be formed on the entire surface of the base material or a part thereof, but it is formed on the wiper sliding surface side of the vehicle windshield glass.
[0042]
The water slidability in the present invention is a scale representing the level of raindrop scattering when these water slidable coatings are put to practical use in vehicle windshield glass, and is indicated by the falling angle evaluated by the method described in the examples. It is.
[0043]
【Example】
Examples of the present invention will be described below. The present invention is not limited to these examples. A method for evaluating a highly durable water slidable coating is shown below.
[0044]
[Evaluation method of highly durable water slidable coating]
(1) Contact angle
The angle formed between the water droplet and the sample surface when about 2 μl of pure water was placed on the sample surface having the water slidable coating was measured with a contact angle meter. In addition, the CA-X type made from Kyowa Interface Science was used for the contact angle meter, and it measured in air | atmosphere (about 25 degreeC).
(2) Fall angle
In a state where the sample was held horizontally, 50 μl of pure water was dropped onto the sample surface, and then the sample was gradually tilted, and the tilt angle at the time when the water droplet started to move was defined as the tumbling angle (°). The sliding angle was measured in the atmosphere (about 25 ° C.) using Kyowa Interface Science CA-A type.
(3) Wiper sliding test
A water pressure of 16 g / cm is applied to a base material on which a highly durable water slidable coating is formed while tap water is sprayed on the coating surface at a rate of 700 ml / min for 45 seconds and 15 seconds. The wiper blade fitted with the natural rubber rubber contacted with was operated using the actual wiper drive system. At this time, the inclination angle of the substrate was about 30 °. As the wiper rubber, Mazda's water-repellent wiper rubber (model, 1UT7-67-33H) was used. At this time, when the wiper blade reciprocated once, the number of times of wiping was set to 1, and the wiper blade was operated at a wiping speed of 48 times / minute.
[0045]
For the coating on the driver's seat, the contact angle and judder evaluation before sliding and after sliding the wiper 270,000 times were performed. In judder evaluation, the lower end of the wiper blade and the entire blade (vibration) are visually observed. The level where there is no chatter and does not hinder driving is good, and large chatter occurs and hinders driving. A certain level was judged as “bad”.
[0046]
Example 1
(1) Preparation of silica sol
Silica sol is tetraethoxysilane [Si (OC ₂ H _Five ) _Four : TEOS] was prepared by advancing hydrolysis and polycondensation reaction. FIG. 1 shows the silica sol preparation procedure and the mixing ratio (weight ratio) of each component.
[0047]
First, TEOS; 312.5 g and Echinene F1 (mixture of lower alcohol composed of 90 wt% ethanol and 10 wt% isopropyl alcohol); 40.0 g were mixed and stirred for about 30 minutes to obtain Solution A. 60% by weight nitric acid aqueous solution; 7.5 g, H ₂ O; 210.0 g and Echinen F1; 20.0 g were mixed and stirred for about 30 minutes to obtain Solution B. Next, after mixing Solution A and Solution B, silica sol was obtained by stirring at room temperature for about 15 hours.
[0048]
(2) Preparation of coating solution
The coating solution was obtained by adding and mixing the silica sol to a mixture obtained by mixing alkoxy group-terminated dimethyl silicone and fluoroalkylsilane. FIG. 2 shows the procedure for preparing the coating solution and the mixing ratio (weight ratio) of each component. In addition, Table 1 shows sample manufacturing conditions.
[0049]
[Table 1]

[0050]
First, heptadecafluorodecyltrimethoxysilane diluted with 1% by weight of ethyl acetate [CF _Three (CF ₂ ) ₇ CH ₂ CH ₂ Si (OCH _Three ) _Three , Hereinafter referred to as “C8FAS”] solution; 0.43 g, alkoxy group-terminated dimethylsilicone having an average degree of polymerization of 250 diluted with ethyl acetate to 0.2 wt% [(CH _Three O) _Three SiCH ₂ CH ₂ {Si (CH _Three ) ₂ O} ₂₅₀ Si (CH _Three ) ₂ CH ₂ CH ₂ Si (OCH _Three ) _Three ] Solution; 0.88 g, methyl ethyl ketone; 7.00 g and isopropyl alcohol; 7.00 g were mixed and stirred for about 5 minutes. Next, 0.78 g of the above silica sol was added and stirred at room temperature for about 15 hours. Next, 27.06 g of methyl ethyl ketone and 27.06 g of isopropyl alcohol were added and stirred for 30 minutes. By the above method, the silica concentration is 0.1% by weight, the weight ratio of the alkoxy group-terminated dimethyl silicone to the silica equivalent of silica sol (hereinafter referred to as “silicone concentration”) is 2.5% by weight, the alkoxy group-terminated dimethyl. A coating solution having an FAS mole ratio to silicone ((number of moles of fluoroalkylsilane) / (number of moles of alkoxy group-terminated dimethylsilicone), hereinafter referred to as “FAS mole ratio”) was 81.
[0051]
(3) Cleaning of glass substrate
The actual windshield size (about 1500 mm × 1000 mm) float glass surface was polished with a polishing liquid, and then washed and dried. In addition, the suspension liquid (1 weight%) which disperse | distributed the abrasive | polishing agent Milleak A (T) for glass (made by Mitsui Metal Mining) to the tap water was used for polishing liquid.
[0052]
(4) Formation of highly durable water slidable coating
The coating solution prepared in (2) above was applied on the glass substrate prepared in (3) above by spin coating. First, a glass substrate is set on a spin coater, about 300 ml of coating solution is dropped while rotating at a rotation speed of 80 rpm, and the coating film is dried while maintaining the rotation speed for 30 seconds. A membrane was obtained. Next, heat treatment was performed at 370 ° C. for 7 minutes, and the glass sample was cooled to room temperature to obtain a colorless and transparent highly durable glass sample with a water slidable coating.
[0053]
When the initial performance and durability of the obtained glass sample with a highly durable water slidable coating were evaluated in the manner described in [Method for evaluating a highly durable slidable coating], as shown in Table 2, the rolling angle was Excellent sliding property was 8 °. Further, as shown in Table 3, in the wiper sliding test, the initial contact angle and the contact angle after sliding 270,000 times showed excellent water repellency of 108 ° and 81 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0054]
[Table 2]

[0055]
[Table 3]

[0056]
Example 2
The procedure was the same as Example 1 except that 0.47 g of C8FAS solution and 0.70 g of alkoxy group-terminated dimethylsilicone solution were used. By the above method, a coating solution having a silicone concentration of 2.0% by weight and a FAS molar ratio of 111 was obtained.
[0057]
As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 9 °, indicating excellent water slidability. Further, in the wiper sliding test, the contact angles at the initial stage and after sliding 270,000 times showed excellent water repellency of 110 ° and 81 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0058]
Example 3
The procedure was the same as Example 1 except that 0.49 g of C8FAS solution and 0.60 g of alkoxy group-terminated dimethylsilicone solution were used. By the above method, a coating solution having a silicone concentration of 1.7% by weight and a FAS molar ratio of 136 was obtained.
[0059]
As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 8 °, indicating good water slidability. Further, in the wiper sliding test, the contact angles at the initial stage and after sliding 270,000 times showed excellent water repellency of 111 ° and 81 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0060]
Example 4
The procedure was the same as Example 1 except that 0.51 g of C8FAS solution and 0.49 g of alkoxy group-terminated dimethylsilicone solution were used. By the above method, a coating solution having a silicone concentration of 1.4% by weight and a FAS molar ratio of 173 was obtained.
[0061]
As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 8 °, indicating excellent water slidability. In the wiper sliding test, the contact angles after initial sliding and after 270,000 sliding were 110 ° and 90 °, respectively, indicating excellent water repellency. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0062]
Example 5
The procedure was the same as Example 1 except that 0.60 g of C8FAS solution and 1.22 g of alkoxy group-terminated dimethylsilicone solution were used. By the above method, a coating solution having a silicone concentration of 3.5% by weight and a FAS molar ratio of 81 was obtained.
[0063]
As a result, a high-quality transparent film was obtained, and the sliding angle was 14 °, indicating excellent water slidability. In the wiper sliding test, the contact angles at the initial stage and after sliding 270,000 times showed excellent water repellency of 109 ° and 87 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0064]
Example 6
All were the same as Example 1 except that 0.51 g of C8FAS solution was used. Further, 1.40 g of n-butanol was added as a dilution solvent. By the above method, a coating solution having a silicone concentration of 2.5% by weight and a FAS molar ratio of 97 was obtained.
[0065]
As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 12 °, indicating excellent water slidability. In the wiper sliding test, the initial contact angle and the contact angle after sliding 270,000 times showed excellent water repellency of 108 ° and 90 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0066]
Example 7
The procedure was the same as Example 6 except that 1.05 g of the alkoxy group-terminated dimethyl silicone solution was used. By the above method, a coating solution having a silicone concentration of 3.0% by weight and a FAS molar ratio of 81 was obtained.
[0067]
As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 13 °, indicating good water slidability. In the wiper sliding test, the initial contact angle and the contact angle after sliding 270,000 times showed excellent water repellency of 108 ° and 85 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0068]
Example 8
The procedure was the same as Example 6 except that 1.41 g of the alkoxy group-terminated dimethyl silicone solution was used. By the above method, a coating solution having a silicone concentration of 4.0% by weight and a FAS molar ratio of 60 was obtained.
[0069]
As a result, a colorless and transparent highly durable water slidable coating film was obtained, and the sliding angle was 14 °, indicating good water slidability. In the wiper sliding test, the initial contact angle and the contact angle after sliding 270,000 times showed excellent water repellency of 108 ° and 87 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0070]
Example 9
The procedure was the same as Example 6 except that 1.76 g of the alkoxy group-terminated dimethyl silicone solution was used. By the above method, a coating solution having a silicone concentration of 5.0% by weight and a FAS molar ratio of 48 was obtained.
[0071]
As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 12 °, indicating excellent water slidability. In the wiper sliding test, the contact angles after initial sliding and after 270,000 sliding were 109 ° and 88 °, respectively, indicating excellent water repellency. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0072]
Example 10
The procedure was the same as Example 6 except that 2.10 g of the alkoxy group-terminated dimethyl silicone solution was used. By the above method, a coating solution having a silicone concentration of 6.0% by weight and a FAS molar ratio of 40 was obtained.
[0073]
As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 13 °, indicating excellent water slidability. In the wiper sliding test, the contact angles at the initial stage and after sliding 270,000 times showed excellent water repellency of 109 ° and 92 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0074]
Example 11
The average degree of polymerization of the alkoxy group-terminated dimethyl silicone is 150 [(CH _Three O) _Three SiCH ₂ CH ₂ {Si (CH _Three ) ₂ O} ₁₅₀ Si (CH _Three ) ₂ CH ₂ CH ₂ Si (OCH _Three ) _Three The procedure was the same as in Example 1 except that By the above method, a coating solution having a silicone concentration of 2.5% by weight and a FAS molar ratio of 49 was obtained. As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 10 °, indicating excellent water slidability. In the wiper sliding test, the initial contact angle and the contact angle after sliding 270,000 times showed excellent water repellency of 108 ° and 87 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0075]
Example 12
The average degree of polymerization of alkoxy group-terminated dimethyl silicone is 200 [(CH _Three O) _Three SiCH ₂ CH ₂ {Si (CH _Three ) ₂ O} ₂₀₀ Si (CH _Three ) ₂ CH ₂ CH ₂ Si (OCH _Three ) _Three Except for the above, everything was the same as in Example 1. By the above method, a coating solution having a silicone concentration of 2.5% by weight and a FAS molar ratio of 65 was obtained. As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 10 °, indicating excellent water slidability. In the wiper sliding test, the initial contact angle and the contact angle after sliding 270,000 times showed excellent water repellency of 109 ° and 86 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0076]
Example 13
The average degree of polymerization of alkoxy group-terminated dimethyl silicone is 300 [(CH _Three O) _Three SiCH ₂ CH ₂ {Si (CH _Three ) ₂ O} ₃₀₀ Si (CH _Three ) ₂ CH ₂ CH ₂ Si (OCH _Three ) _Three Except for the above, everything was the same as in Example 1. By the above method, a coating solution having a silicone concentration of 2.5% by weight and a FAS molar ratio of 97 was obtained. As a result, a colorless and transparent and highly durable water slidable film was obtained, and the sliding angle was 11 °, indicating excellent water slidability. In the wiper sliding test, the initial contact angle and the contact angle after sliding 270,000 times showed excellent water repellency of 108 ° and 88 °, respectively. The judder evaluation was “good” even after sliding 270,000 times, indicating an excellent anti-judder performance.
[0077]
Comparative Example 1
All were the same as Example 1 except that 0.88 g of an alkoxy group-terminated dimethyl silicone (average polymerization degree 250) solution diluted to 4 wt% of C7FAS solution was added. By the above method, a coating solution having a silicone concentration of 50% by weight and a FAS molar ratio of 2.6 was obtained.
[0078]
As a result, a colorless and transparent film was obtained, and the sliding angle was 8 ° and the sliding property was good. In the wiper sliding test, the judder evaluation was “good” even after sliding 270,000 times and showed excellent judder prevention performance, but the contact angle after sliding 270,000 times was remarkably deteriorated to 55 °. A coating that can be provided could not be obtained.
[0079]
Comparative Example 2
All were the same as in Example 1 except that the average degree of polymerization of the alkoxy group-terminated dimethyl silicone was 200, and the addition amount of the solution was 0.18 g. By the above method, a coating solution having a silicone concentration of 0.5% by weight and a FAS molar ratio of 550 was obtained.
[0080]
As a result, a good quality transparent film was obtained, but the sliding angle was 20 ° and the sliding property was poor. Further, in the wiper sliding test, the contact angles at the initial stage and after sliding 270,000 times showed excellent water repellency of 111 ° and 87 °, respectively. Therefore, the anti-judder performance is not sufficient and a film that can be used practically cannot be obtained.
[0081]
Comparative Example 3
All were the same as Example 1 except that the silicone concentration was 0% by weight. That is, in this comparative example, a coating containing only fluoroalkylsilane and not containing alkoxy-terminated dimethylsilicone in a matrix made of silica was produced. As a result, spotted marks were generated on the entire surface of the coating. Further, the initial sliding angle was 27 ° and the sliding property was poor. Further, in the wiper sliding test, the contact angles at the initial stage and after sliding 270,000 times showed excellent water repellency of 113 ° and 100 °, respectively. Therefore, the anti-judder performance is not sufficient and a film that can be used practically cannot be obtained.
[0082]
Comparative Example 4
The same as Example 1 except that the silica concentration was 0 wt%. That is, in this comparative example, a film not containing silica as a matrix component was produced. As a result, although a colorless and transparent film could be obtained, the contact angle was 78 ° and the sliding angle was 20 °, both water repellency and water slidability were poor, and a film that could be used practically could not be obtained.
[0083]
【The invention's effect】
The highly durable water slidable coating of the present invention has high water repellency, water slidability, and excellent wear resistance due to wipers and the like, and additionally prevents judder from being generated when the wiper slides. When it is used for shield glass, it is easy to secure the front view in the rain, and the safety of driving is improved without worrying about the wiper judder. Furthermore, there are significant effects that this effect can be maintained over a long period of time.
[Brief description of the drawings]
1 is a diagram showing a preparation procedure of silica sol in Example 1. FIG.
FIG. 2 is a diagram showing a procedure for preparing a coating liquid in Example 1.

Claims (3)

A water-slidable coating for use in a windshield glass for vehicles, the coating comprising a silica sol serving as a matrix, an alkoxy group-terminated dimethyl silicone represented by the general formula [1], and a fluoroalkyl represented by the general formula [2] A coating solution obtained by mixing with silane, wherein the alkoxy group-terminated dimethylsilicone is mixed in a proportion of 0.1 wt% to 100 wt% with respect to the silica equivalent of silica sol, and the fluoroalkylsilane is alkoxy A coating formed by applying a coating solution mixed in an amount of 20 to 200 mol to 1 mol of base terminal dimethylsilicone on a sliding surface of a windshield glass wiper for vehicles. A highly durable water slidable coating characterized by preventing the occurrence of water.

Here, A ¹ and A ² are each a divalent hydrocarbon group, a — (CH ₂ ) _i —NH—CO—O— group (i is an integer of 0 to 9), or oxygen. R ¹ and R ² are each a monovalent hydrocarbon group, and n is an integer of 2000 or less and represents the average degree of polymerization. Further, p and q are each an integer of 0 to 3, and the sum of p and q is 3 or more.

Here, B is —CF ₃ group, or —CH ₂ CH ₂ Si (CH ₃ ) _{3 -t} Y _t group, X and Y are monovalent hydrolyzable groups, t is an integer of 1 to 3, and r is Integer of 0-12, s is an integer of 1-3. 2. The highly durable water-slidable coating according to claim 1, wherein the average polymerization degree of the alkoxy group-terminated dimethyl silicone is 50 to 1,000. (1) A step of preparing a silica sol that becomes a matrix of a coating by hydrolyzing and polycondensing alkoxysilane; (2) an alkoxy group-terminated dimethyl silicone represented by the general formula [1] The silica sol prepared in the step (1) is added to and mixed with the fluoroalkylsilane represented by the formula (1), and a coating solution is prepared by (3) the substrate in the step (2). The method for forming a highly durable water-slidable coating according to claim 1 or 2, wherein the coating is formed by applying a heat treatment at 80 ° C to 600 ° C after applying the prepared coating solution.

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